CEOs are limited in making policy changes regarding climate change by all of the following EXCEPT .

b. the necessity to think in the long term rather than the short term

Explanation:

There are policy changes that a company can make that will result in them having lower profits. For this reason, the CEO might face opposition or limitations from certain people or principles in implementing such changes.

The Board of Directors is one such limitation as they owe it to the shareholders to maximise their wealth and if climate change policy might hinder that, they might limit the policy. This reason is the same for any limitation from investor support which is linked directly to profits.

The CEO also has the same fiduciary responsibility to maximise shareholder wealth as well. The only option which is not a limiting factor therefore is the necessity to think in the long term rather than the short term.